Selective hydrogenation over alumina-supported catalysts having substantial area in large pores

ABSTRACT

Catalysts comprising iron, nickel or cobalt, and antimony or arsenic supported on alumina having relatively few pores smaller in diameter than 500 A and a surface area not less than 2 M2/g contributed by pores having diameters larger than about 500 A are used for selective hydrogenation of hydrocarbons.

iJnifiad Sfiaies P6601111 Pitzer Apr. 10, 1973 [541 SELECTWEHYDROGENATION QVER 3,671,597 6 1972 Kroll ..260/683.2 xALUMlNA-SUPPORTED CATALYSTS 2,359,759 10/1944 l-lebbard et a1 ..260 677H QRE 2,402,493 6/ 1946 Greensfelder et al ..260/677 H X ANTEAL A m2,802,889 8/1957 Frevel et a1 ..260/677 l-l 3,463,830 8/1969 Dunning eta1. ..260/683.2 X Inventor; Emory w Pfizer Bartlesville lrnoto Ct X3,514,497 5/1970 Hughes ..260/683.2 X [73] Assignee: Phillips PetroleumCompany,

Bartlesville, Okla. Primary ExaminerDaniel E. Wyman AssistantExaminerPaul F. Shaver [22] Filed. Oct. 16, 1970 AnOmey YOung & gg 21]Appl. No.: 81,600

[57] ABSTRACT 52 US. Cl. ..260/677 H, 260/666 A, 260/680 R, Catalystscomprising iron, nickel or cobalt, and 26O/683 2 timony or arsenicsupported on alumina having rela- 51 Im. Cl ..C07c 11/02 t61y few P0resSmaller in diameter than 500 A and a 58] Field of Search 260/677 H 683 2surface area not less than 2 M lg contributed by pores having diameterslarger than about 500 A are used for selective hydrogenation ofhydrocarbons.

[56] References Cited 10 Claims, No Drawings UNITED STATES PATENTS3,636,175 1/1972 Nowack ..260/666 A SELECTIVE HYDROGENATKON OVERALUMINA- SUPPORTED CATALYSTS HAVING SUBSTANTIAL AREA IN LARGE PORES Thisinvention relates to selective hydrogenation of hydrocarbons.

In one of its more specific aspects, this invention relates to theselective hydrogenation of hydrocarboncontaining streams overalumina-supported nickel-arsenic catalysts having a substantial surfacearea in large pores.

It is known that catalysts comprising antimony and arsenic supported onalumina are useful for selective hydrogenation. For example,1,5-cyclo-octadiene can be selectively hydrogenated by nickel incombination with arsenic and alumina to cyclooctene, mixed olefins canbe treated to reduce their content of sulfur compounds and carbonylcompounds, and acetylene can be selectively hydrogenated in ethylenestreams. Similarly, such catalysts can also be used for the double bondisomerization of pentenes and for the selective hydrogenation of dienesin monoolefin streams.

Relatedly, catalysts comprising iron and arsenic supported on aluminaare known to be effective in the selective hydrogenation of acetylenesin a diolefin stream.

This invention is directed to the discovery that this class ofcatalysts, as hereinafter defined, and these types of reactions, areimproved if the support, preferably an alumina support, has relativelyfew or, preferably, has substantially no pores smaller in diameter than500 A and has a surface area not less than 2 m /g concentrated in poreshaving diameters larger than about 500 A. In other words, a substantialnumber of pores of the catalyst are at least 500 A in diameter and thesepores contribute to the catalyst a surface area of at least 2 m /g.

Catalysts in which the alumina possesses these properties can beemployed at lower reaction temperatures and with lower loading ofnickel, iron and/or cobalt and antimony and/or arsenic than can beemployed with the conventional aluminas which possess a relatively highsurface area in a large number of small pores. Further, the loss of theaforementioned elements from the catalyst during service is minimizedwhen employing the catalyst of this invention.

Commercially employed catalytic aluminas generally have comparativelylarge surface areas of from about 50 to about 200 m /g, this surfacearea being provided by the presence of an extremely large number ofpores having diameters less than 500 A and generally less than about 300A.

The aluminas of the present invention, in contrast, have few andpreferably no pores having diameters less than about 500 A.Consequently, the aluminas of this invention have relatively low surfaceareas. The aluminas of the present invention will have a total surfacearea of at least 2 m /g and up to m lg or greater. The aluminas canintially possess such pore size distribution and surface areas or can bemodified to the defined condition. It is to be understood that thealuminas which will possess the defined surface areas are not thoseinactive aluminas, such as the inert alpha-aluminas devoid ofsignificant surface area, not practically employed as catalyst supports.

The aluminas can be modified to impart to them the defined pore sizedistribution and surface area in several ways. One method involvescollapsing the small pores by sintering. Another method involves steamtreatment at temperatures of about l,300 to about 1,600 E, at whichtemperature the small pores can be collapsed and/or new larger pores canbe formed. Other methods of pore-size adjustment can also be employedsuch as the treatment of inactive alpha-alumina with nitric acid orammonium nitrate as shown in US. Pat. No. 2,800,518.

The catalyst of the present invention comprises the above-definedalumina associated with at least one of nickel, cobalt and iron and atleast one of arsenic and antimony. Such catalysts, while convenientlyreferred to as arsenides or antimonides of nickel, cobalt and iron, donot necessarily contain those elements in stoichiometric proportions ofsuch compounds. In general, the catalyst composite will be comprised offrom about 0.001 to about 20, preferably from about 0.1 to about 3,weight percent of the nickel, cobalt or iron, or their mixture,calculated as the element, based upon the weight of the total composite.The arsenic or antimony, or their mixture, will be present in amountswithin the range of about 0.001 to about 30, preferably from about 0.1to about 3, weight percent based upon the weight of the total composite.

The nickel, cobalt or iron, or their mixtures can be brought intoassociation with the alumina by a number of known methods. They can bedeposited simultaneous with the arsenic and/or antimony bycoimpregnation or by coprecipitation, either in inorganic or organicforms from inorganic or organic media. Similarly, coimpregnation orcoprecipitation can be carried out in a plurality of steps in any one ofwhich any desired component can be associated with the alumina.

Whatever the method of preparation, the catalyst is washed free ofundesirable nonvolatile materials, dried and calcined at the usualtemperatures in air. Thereafter, the catalyst is reduced in hydrogen byconventional techniques, for example, in a stream of hydrogen at about 750 F. for 12 hours.

The catalyst of this invention can be employed in any form such aspellets, and in forms of any size.

The catalysts of this invention can be employed in the treatment of alarge number of feedstocks. It is applicable to the selectivehydrogenation of olefinic feedstocks and to the hydrogenation ofacetylenic compounds, organic sulfur compounds, organic peroxides,carbonyl compounds, cyclic and acyclic polyenes and the like, containedin feedstocks of any nature.

Depending upon the purpose for which the invention is employed, theapplicable feedstream is brought into contact with hydrogen and with thecatalyst at a temperature within the range of about F. to about 750 F.,preferably from about F. to about 500 F. at a The process can be carriedout employing the catalyst as a fixed bed and the desired products canbe recovered from the reaction effluent with any portion of the effluentbeing recycled to the reaction zone.

The method of this invention is illustrated by the following example inwhich comparative data are presented for three catalysts, one of whichwas the catalyst of this invention.

EXAMPLE The following data present the results of individual runs madewith each of three catalysts. Two of the catalysts, catalysts A and B,were substantially identical but were subjected to different periods ofoperation.

Catalyst C is the catalyst of this invention.

Catalysts A and B were individually prepared by dissolving 98.5 g ofNi(NO '6H O in 1,200 ml of water. Flame-hydrolyzed alumina (Alon C) inan amount of 150 g was stirred into the solution and 32.1 g of H AsO in300 ml water were added to the mixture. A 14 percent aqueous ammoniumhydroxide was added until the pH of the mixture was between 6.5 and 7.0.The mixture was diluted with water to a total volume of 3,500 ml,thoroughly stirred and filtered. The filter cake was dried and ground toabout 8-20 mesh.

Catalyst C, the catalyst of this invention, was prepared by dissolving3.4 g H AsO in 100 ml water in which solution 12.3 g Ni(NO -6H O weredissolved. About 100 g large pore alpha-alumina in the form ofone-eighth inch diameter cylinders were introduced into the solution inwhich they were allowed to stand for a sufficient period to insureimpregnation. The unabsorbed solution was removed from the aluminacylinders, the cylinders were substantially dried and then heated to1,000" F. at which temperature they were maintained for 30 minutes.

Each of catalysts A, B and C was placed individually in a fixed bedreactor and reduced by passing hydrogen in contact with the catalyst ata rate of about 2,700 Gl-lSV, at a temperature of 800 F. and at apressure of about 350 psig for about 16 hours. The temperature of eachcatalyst was then reduced to about 150 F.

Each catalyst was then individually contacted with a feed comprising,volumetrically, 33 percent ethylene, 66 percent hydrogen, 1,000 ppmacetylene, 1,000 ppm carbon monoxide and 100 ppm ethane at the operatingconditions listed below. The feed was introduced at a gaseous hourlyspace velocity of 5,000 with the reaction temperature being adjusted ineach instance to maintain the acetylene content in the reactor effluentat 1 ppm or less.

Operating conditions and results were as follows:

Catalyst A B C Catalyst Properties, New

Surface Area, mlg

in pores l000 A dia. 0.1 (estimated) 0.1 2.4 in pores 500 A dia. 1.0(estimated) 1.0 2.8 in pores 20 A dia. 70 (estimated) 70 4.7 CompostiionNickel, Wt. 9.8 (estimated) 9.8 0.94 Arsenic, Wt. 9.1 (estimated) 9.10.66 Operating Conditions Temperature, F. 220 224 189 Product AnalysisAcetylene, ppm 1 1 1 Ethane, Wt. 0.03 0.22 0.03 Catalyst Properties,Used After hours use 1 1 1 740 363 Nickel, Wt. 8.6 8.4 0.89 Arsenic, Wt.6.3 4.3 0.54

In the above data, surface area determinations in pores greater than 500and 1,000 A in diameter was determined by mercury intrusion, that inpores greater than 20 A in diameter was determined by nitrogenadsorption, the latter values being substantially a measure of the totalsurface area.

The above data indicate that the catalyst of this invention has agreater ability than the comparison catalysts to hydrogenate theacetylene at low temperature. Further, this was accomplished atconsiderably lower loading of the catalyst with nickel and arsenic.Additionally, the loss of arsenic from the catalyst of this inventionwas considerably less in terms of percent loss per hour of operatingtime than was the loss experienced by the comparison catalysts.

In consideration of the above results in view of the substantialdifferences in nickel and arsenic content of the catalysts, the catalystof the present invention is a decidedly superior catalyst.

It will be evident from the foregoing that various modifications can bemade to the method of this invention. Such, however, are considered asbeing within the scope of the invention.

What is claimed is:

l. The method of hydrogenating conjugated dienes contained in afeedstream comprising monoolefins which comprises contacting saidfeedstream with hydrogen and a catalyst consisting essentially of aporous alumina support, at least one metal selected from the groupconsisting of nickel, iron and cobalt and at least one material selectedfrom the group consisting of antimony and arsenic under hydrogenatingconditions, said catalyst being in a reduced state, a substantialportion of the surface area of said support being in pores having adiameter not less than 500 A, said pores of said diameter comprising asurface area of not less than 2 lg square meters per gram of saidcatalyst.

2. The method of claim 1 in which said support has a surface area withinthe range of from about 2 to about 10 square meters per gram.

3. The method of claim 1 in which said support has a surface area ofabout 2.4 square meters per gram in pores having diameters greater than1,000 A, a surface area of about 2.8 square meters per gram in poreshaving diameters greater than 500 A and a surface area of about 4.7square meters per gram in pores having diameters greater than 20 A.

4. The method of claim 1 in which said metal is present in an amountwithin the range of from about 0.001 to about 20 weight percent of saidcatalyst and said material is present in an amount within the range offrom about 0.001 to about 30 weight percent of said catalyst.

5. The method of claim 1 in which said catalyst contains a mixture ofnickel, cobalt and iron and a mixture of arsenic and antimony.

6. The method of claim 5 in which said mixture of nickel. cobalt andiron is present in an amount within the range of from about 0.001 toabout 20 weight percent of said catalyst and said mixture of arsenic andantimony is present in an amount within the range of from about 0.001 toabout 30 weight percent of said catalyst.

7. The method of claim 5 in which said mixture of nickel, cobalt andiron is present in an amount within the range of from about 0.1 to about3 weight percent timony is present in an amount of about 0.66 weightpercent.

10. The method of claim 1 in which the surface area of said support isimparted to said support by collapsing small pores to form large poresor by contacting said support with steam at elevated temperatures toform new pores.

2. The method of claim 1 in which said support has a surface area withinthe range of from about 2 to about 10 square meters per gram.
 3. Themethod of claim 1 in which said support has a surface area of about 2.4square meters per gram in pores having diameters greater than 1,000 A, asurface area of about 2.8 square meters per gram in pores havingdiameters greater than 500 A and a surface area of about 4.7 squaremeters per gram in pores having diameters greater than 20 A.
 4. Themethod of claim 1 in which said metal is present in an amount within therange of from about 0.001 to about 20 weight percent of said catalystand said material is present in an amount within the range of from about0.001 to about 30 weight percent of said catalyst.
 5. The method ofclaim 1 in which said catalyst contains a mixture of nickel, cobalt andiron and a mixture of arsenic and antimony.
 6. The method of claim 5 inwhich said mixture of nickel. cobalt and iron is present in an amountwithin the range of from about 0.001 to about 20 weight percent of saidcatalyst and said mixture of arsenic and antimony is present in anamount within the range of from about 0.001 to about 30 weight percentof said catalyst.
 7. The method of claim 5 in which said mixture ofnickel, cobalt and iron is present in an amount within the range of fromabout 0.1 to about 3 weight percent of said catalyst and said mixture ofarsenic and antimony is present in an amount within the range of fromabout 0.1 to about 3 weight percent of said catalyst.
 8. The method ofclaim 3 in which said catalyst contains about 0.94 weight percent nickeland about 0.66 weight percent arsenic.
 9. The method of claim 5 in whichsaid mixture of nickel, cobalt and iron is present in an amount of about0.94 weight percent and said mixture of arsenic and antimony is presentin an amount of about 0.66 weight percent.
 10. The method of claim 1 inwhich the surface area of said support is imparted to said support bycollapsing small pores to form large pores or by contacting said supportwith steam at elevated temperatures to form new pores.